A contactor or a relay is generally used for switching on and switching off or controlling a working circuit. For example, the contactor is provided with a coil, a moving contact and a fixed contact. When current passes through the coil in the contactor, a magnetic field can be produced to connect the moving contact and the fixed contact, thereby controlling a loaded electric appliance.
Due to frequent connection and disconnection, welding adhesion between the current conduction contacts of a high-voltage and high-current contactor or relay may occur due to overcurrent, high-temperature electric arc destruction or aging after long-term use or other reasons. As a result, the moving contact of the contactor or the relay is out of control and thus fails. For a low-voltage relay or contactor, usually the failure can be directly detected very simply by monitoring the circuit. But for the high-voltage and high-current contactor, it is inconvenient to directly monitor the circuit.
Generally, in the industry, the moving contact end of the contactor is in parallel connection with an auxiliary contact which is insulated and isolated with the main contact such that the connection and disconnection of the main contact is detected by monitoring the connection and disconnection of the auxiliary contact. In addition, in the industry, the position or the connection or disconnection of the main contact is sensed by adding a non-contact type of magnetic Hall switch. Although these approaches are simple for customers to employ, the cost of the contactor and the maintenance cost of a product are relatively high; and furthermore, when high current flows through the relay or the contactor, the magnetic Hall switch is very liable to being interfered by magnetic lines and thus cannot meet the requirement of controlling the contactor. Furthermore, as the control functions of the contactor increase, the requirement on effective control of the contacts is higher.
In most cases, the contactor or the relay is connected with various control circuits for achieving various control functions. For example, for the high-current contactor, in particular to the contactor applied to a mobile device, such as an electric vehicle, the average driving current of the contactor is required to be as low as possible. Generally, an electronic power-saving device is used to meet the requirement. For existing contactors, the electronic device is generally arranged in a contactor or directly attached on the contactor, and is energized to start to work. With such configurations, it is simple for users to use the existing contactors. However, the cost of the existing contactors and the maintenance cost of a product are relatively high. Moreover, when the contactor or the relay is configured with a variety of control circuits, the wiring arrangement and the circuit connection become complex, which causes the cost of the contactor or the relay to increase. In addition, in the development of miniaturization, simplification and universalization of the contactor or the relay, the development of diversification of the control circuit of the contactor or the relay is limited.